Video and graphic display systems are rapidly becoming the most important source of information, communication, and entertainment in today's society. The growing demand for new visual services and applications imposes a high level of complexity and performance on such display systems.
Advances in image processing and memory technology have produced continuous improvements in picture quality and display capabilities for two apparently unrelated classes of visual signals: full motion video signals and high resolution still images (text, graphics, and pictures). However, there is a general lack of signal and raster processing technology that can simultaneously satisfy the different spatial and temporal requirements of the video and still image signals. This makes the composition of still images and video for display on a single high resolution output raster a difficult task. Research efforts to define and develop integrated still image and video user interfaces have only just started and have generally not yielded entirely satisfactory results. (See e.g. N. Tanaba et al. "How to Build a Mixed Mode Terminal -Basic Concepts and an Example", Proceedings of Globecome '86, pp. 471-478, Dec. 1986 and S. Tsurauta et al, "Intelligent Communications Terminal for Integrating Voice, Data, and Video Signals", Proceedings of ICC '86, pp. 1509-1513, June 1986.)
Still imagery composition on engineering work stations, personal computers and graphic production systems benefits from the use of high resolution displays. However, a basic deficiency of these systems is the inability to accept video signals as inputs and manipulate them as windows on the display.
Today's video production industry makes use of video special effects processors that can compose several overlapping video windows. Examples of such special effects processors are the Ampex Corporation ADO system and Abakus Video System A52 processor. (A further example of a television special effects system is disclosed in McCoy U.S. Pat. No. 4,266,242.) To enter still imagery into the compositions produced by such video special effects systems, the still image is converted into a video signal that may be manipulated as any other video signal. Typically, the resolution of the images produced by such special effects systems is limited by the quality of the 525 or 625 line video format used throughout the processor. Furthermore, such existing video effects systems can only assemble a few video signals at a time (typically a maximum of four or five) so that the maximum number of still image windows is also limited to this number. While more complex compositions can be built with the aid of video tape recorders in the television production environment, this is inadequate for interactive visual applications dominated by still image windows.
Auxiliary processors to overlay a full motion video window on the display of a graphics workstation are also becoming increasingly available. Examples of this approach include the NEC EWS-E Advanced Workstation of NEC Information Systems, Inc. and the 1280/640 series processors of Parallax Graphics. While a significant step towards media integration, the integration is not achieved without a penalty in picture quality and composition flexibility. Video is treated as a special case, not subject to the workstation's agile ability to format text, graphics and pictures.
In view of the above, it is an object of the present invention to provide a system that can flexibly compose video and still image signals to form a single integrated display. More particularly, it is an object of the present invention to provide a system for composing a plurality of video and still image signals including text and graphics into a full color High Definition Television display. It is a further object of the invention to provide a display system which enables the dynamic allocation of display area to multiple windows of video and still images.